Brocade FICON Administrator's Guide v7.1.0 (53-1002753-01, March 2013)

50 FICON Administrator’s Guide
53-1002753-01
FICON emulation overview
4
For information on configuring tape emulation, refer to “Configuring FICON emulation” on page 54.
For information on displaying tape emulation status and statistics, refer to “Displaying FICON
emulation performance statistics” on page 55.
Tape Write Pipelining
FICON Tape Write Pipelining (refer to Figure 12)improves performance for a variety of applications
when writing to tape over extended distances. FICON Tape Write Pipelining locally acknowledges
write data records, enabling the host to generate more records while previous records are in transit
across the IP WAN. If an exception status is received from the device, the writing of data and
emulation is terminated.
FIGURE 12 Tape Write Pipelining
Tape Read Pipelining
FICON Tape Read Pipelining (Figure 13 on page 51) improves performance for certain applications
when reading from FICON tape over extended distances. FICON Tape Read Pipelining reads data on
the tape directly from the tape device. Reading of the tape continues until a threshold is reached.
The buffered data is forwarded to the host in response to requests from the host. When the host
sends the status accept frame indicating that the data was delivered, the read processing on the
device side credits the pipeline and requests more data from the tape. If an exception status is
received from the device, the reading of data and emulation is terminated.
Brocade
extension blade
with emulation
for FICON
FICON
Director(s)
Brocade
extension switch
with emulation
for FICON
Virtual Tape
Controller
Tape
Library
System z
hosts
Local acknowledgements
Write sequences are pre-acknowledged
to host and data is continuously sent
to the network
IP network
1
2
3
Final ending status is
presented to host
4a
Write data is streamed
to remote device
1a
2a
3a
Final ending status is
returned to local device
4
Local acknowledgement
Write commands
Write channel programs
are presented to
the tape device
1b
2b
3b